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Thèse Philippe Lefort

3 juillet 2014

Analyse des écoulements eau gaz dans les argilite du Callovo-Oxfordien à l’aide de la théorie de la percolation en gradient

Philippe Lefort

Mercredi 16 juillet à 10 h 30 Amphithéâtre Nougaro

Sous réserve d’autorisation de soutenance par les rapporteurs

Résumé :

The work presented in this manuscript is motivated by the study of nuclear waste underground repository. In this context, we study the hyperslow drainage problem, which is related to the gas production, mainly hydrogen, taking place within the repository. Although the gas production rate is quite small, and thus the drainage hyperslow, the amount of produced gas is quite significant because the production takes place over thousands years.
The study is performed within the framework of the theory of invasion percolation in a gradient. We first show that the hyperslow drainage process can be modelled using the traditional two-phase flow model based on the generalized Darcy’s law. A crucial step is then to specify properly the parameters of the model. We show how they must be specified from
the asymptotic behaviours of the parameters for an infinite medium as predicted by percolation theory. The obtained solution indicates that the hyperslow drainage operates in the vicinity of breakthrough pressure, which is the subject of a specific study. Furthermore, the hyperslow drainage is characterized by a weak desaturation of the medium and a great
sensitivity to the model parameters in the range of high wetting fluid saturation.
We also study the impact of coupling between the flow and the local deformation of porous matrix at the pore network scale from numerical simulations using a model coupling a pore network model and a deformation model based on a system of interconnected springs. The simulations indicate a major change of the invasion pattern compared to the rigid matrix with
the self-generation of invasion preferential paths when the coupling is sufficiently strong.

Jury :

Patrice Creux - Maître de Conférences

Jean-François Daïan - Maître de Conférences

Marc Prat - Directeur de Thèse

Jean Talandier - Ingénieur Recherche ANDRA

Joel Billiotte - Maître de Recherche ENSMP

Henri Bertin - Directeur de Recherche

Frédéric Skoczylas - Professeur